The human body contains a number of glands including the lacrimal and meibomian glands of the eye, the sebaceous or pilo-sebaceous hair glands on the face and underarms, and the mammary glands in the breasts. These glands may malfunction due to age, irritation, environmental conditions, cellular debris, inflammation, hormonal imbalance and other causes. One common malfunction is the restriction or stoppage of the natural flow of secretions out of the gland. The present invention provides methods and modalities to enhance and/or restore the natural flow of secretions out of the glands.
While the description that follows is directed to the meibomian glands of the eye, it will be understood that the present invention may be employed to treat all of the external glands of the body. With particular reference to the human eye, the tear film covering the ocular surfaces is composed of three layers. The innermost layer in contact with the ocular surface is the mucus layer. The middle layer comprising the bulk of the tear film is the aqueous layer, and the outermost layer is a thin (less than 250 nm) layer comprised of many lipids known as “meibum” or “sebum”. The sebum is secreted by the meibomian glands, enlarged specialized sebaceous-type glands (hence, the use of “sebum” to describe the secretion) located on both the upper and lower eye lids, with orifices designed to discharge the lipid secretions onto the lid margins, thus forming the lipid layer of the tear film. The typical upper lid has approximately 25 meibomian glands and the lower lid has approximately 20 meibomian glands, which are somewhat larger than those located in the upper lid. The meibomian gland comprises various sac-like acini which discharge the secretion into the duct of the gland. The secretion then passes into the orifices which are surrounded by smooth muscle tissue and the muscle of Riolan which are presumed to aid in the expression of sebum. The meibomian gland orifices open on the lid margin usually along the mucocutaneous junction also known as the gray line. The meibomian gland orifices are assumed to open with blinking and release minute amounts of sebum secretions onto the lid margin and then into the inferior tear meniscus. The lipid “sebum” in the tear meniscus is spread upward and over the tear film of the open eye by the upward blink action. If the lipid secretions are optimal, and adequate lipid layer is maintained at the air interface to minimize evaporation and prevent dry eye states. If the lipid secretions are inadequate the lipid layer is not adequate to minimize evaporation with resulting rapid evaporation leading to dry eye states. Thus, it will be seen that a defective lipid layer or an incorrect quantity or quality of such lipids can result in accelerated evaporation of the aqueous layer which, in turn, causes symptoms which may include symptoms such as dryness, scratching, irritation, burning, tearing, redness, and itchiness, which are collectively be referred to as “dry eye” symptoms.
Dry eye states have many etiologies. A common cause of common dry eye states is the condition known as “meibomian gland dysfunction”, a disorder where the glands are obstructed or occluded. As employed herein the terms “occluded” and “obstruction” as they relate to meibomian gland dysfunction are defined as partially or completely blocked or plugged meibomian glands. If completely obstructed the gland cannot secrete. If partially or intermittently occluded the gland may secrete either normal or decreased amounts of sebum. More usually the secretions are altered having semi-solid, thickened, congested secretions, frequently described as inspissated. The secretions may be clear or yellowish, the latter indicating possible infection. Meibomitis, an inflammation of the meibomian glands leading to their dysfunction, is usually accompanied by blepharitis (inflammation of the lids). Meibomian gland dysfunction may accompany meibomitis, or meibomian gland dysfunction may be present without obvious lid inflammation. Meibomian gland dysfunction is frequently the result of keratotic obstruction of the individual meibomian gland orifices and/or the central duct (canal) of the gland which compromises the secretory functions of the individual meibomian glands. More particularly, these keratotic obstructions include a combination of desquamated epitlelial cells, keratin, sebaceous ground substance, and bacteria, see, Korb et al., Meibomian Gland Dysfunction and Contact Lens Intolerance, Journal of the Optometric Association, Vol. 51, Number 3, (1980), pp. 243-251. While meibomitis is obvious by inspection of the external lids, meibomian gland dysfunction may not be obvious even when examined with the magnification of the slit-lamp biomicroscope, since there may not be external signs or the external signs may be so minimal that they are overlooked. The external signs of meibomian gland dysfunction may be limited to subtle alterations of the meibomian gland orifices, subtle or pronounced overgrowth of epithelium over the orifices, and pouting of the orifices of the glands with congealed material acting as the obstructive material under the epithelia overgrowth resulting in the pouting of the orifices.
Hormonal changes include those which occur during menopause, and particularly changing estrogen levels, can result in thickening of the oils secreted by the meibomian glands which results in clogged gland orifices. Further, decreased estrogen levels may also enhance conditions under which staphylococcal bacteria can proliferate. This can cause migration of the bacteria into the glands, thus resulting in a decreased secretion rate.
When the flow of secretions from the meibomian gland is restricted due to the existence of an obstruction, epithelial cells on the eyelid margin tend to grow over the gland orifice thus further restricting sebum flow and exacerbating the dry eye condition.
Additional factors which may cause or exacerbate meibomian gland dysfunction include, age, contact lens wear and hygiene, disorders of blinking, extended computer use, cosmetic use, or other illness, particularly diabetes.
Clinical evaluation of the meibomian glands requires the application of pressure to the external surface of the eyelids over the meibomian glands in order to determine whether secretion is obtained from the individual gland with gentle pressure. If gentle pressure does not provide secretion, forceful expression may be utilized to determine if secretion can be obtained. Thus, the state of an individual meibomian gland can vary from optimal, where clear meibomian sebum is expressed with gentle pressure; to mild or moderate meibomian gland dysfunction where milky fluid or inspis sated or creamy secretion may be obtained; to total blockage where no secretion of any sort can be obtained even with the application of extreme pressure (see Korb, et al., “Increase in Tear Film Lipid Layer Thickness Following Treatment of Meibomian Gland Dysfunction”, Lacrimal Gland, tear Film, ad Dry Eye Syndromes, pp. 293-298, Edited by D. A. Sullivan, Plenum Press, New York (1994)). Significant chemical changes of the meibomian gland secretions occur with meibomian gland dysfunction and consequently, the composition of the naturally occurring tear film is altered, which in turn, contributes to ocular disease which is generally known as “dry eye”.
While the tear film operates as a singular entity and all of the layers thereof are important, the lipid layer, which is secreted from the meibomian glands is of particular significance as it functions to slow the evaporation of the underlying layers and to lubricate the eyelid during blinking which prevents dry eye.
In response to the foregoing, various treatment modalities have been developed in order to treat the dry eye condition, including drops which are intended to replicate and replace the natural tear film, pharmaceuticals which are intended to stimulate the gland and cells providing the components of the tear film and various warm compresses and warming devices which are designed to treat meibomitis and the meibomian glands.
Eye drops such as Refresh®, Soothe® and Systane® are designed to closely replicate the naturally occurring healthy tear film. However, their use and administration is merely a treatment of symptoms and not of the underlying cause. Further, the use of drops is generally for an indefinite length of time and consequently, extended use can become burdensome and costly. Pharmaceutical modalities such as the use of tetracycline have also been suggested to treat meibomian gland dysfunction and one such treatment is disclosed in United States Patent Publication no. US2003/011426 titled “Method for Treating Meibomian Gland Disease”, U.S. Pat. No. 6,455,583 titled “Method for Treating Meibomian Gland Disease” to Pflugfelder et al. and PCT Publication No. WO 99/58131 titled “Use of Tetracyclines for Treating Meibomian Gland Disease”. However, this treatment has not proven to be clinically effective for meibomian gland obstruction, and it may be unnecessary as much meibomian gland dysfunction is the result of an obstruction of the gland without infection. The use of corticosteroids have also been proposed to treat meibomian gland dysfunction as disclosed in U.S. Pat. No. 6,153,607 titled “Non-preserved Topical Corticosteroid for Treatment of Dry Eye, filamentary Keratitis, and Delayed Tear Clearance (or Turnover) to Pflugfelder et al. Again, this proposed treatment appears to treat the symptom of dry eye, as opposed to treatment of the underlying cause and further presents the risks of inducing cataracts and glaucoma. Additionally, the use of topically applied androgens or androgen analogues have also been used to treat acute dry eye signs and symptoms in Keratoconjuctivitis Sicca as disclosed in U.S. Pat. Nos. 5,958,912 and 6,107,289 both titled “Ocular Therapy in Keratoconjunctivitis Sicca Using Topically Applied Androgens of TGF-β” and both issued to Sullivan.
Another modality for the treatment of meibomian gland dysfunction is disclosed in European Patent Application serial no. PCT/GB2003/004782 titled “Eyelid Margin Wipes Comprising Chemical Means for Temperature Adjustment”. As disclosed in this patent application, an eyelid margin wipe is provided wherein prior to use, a chemical agent is activated that will heat the wipe to about 32° C. to about 55° C. and wherein the temperature will be maintained for at least ten minutes to treat the eyelid margin. This method is not without its drawbacks in that lid irritation can be exacerbated by non-specific heating and the heating range noted as comfortable at over 50° C. would burn the skin. Another method of heating the eyelids and meibomian glands uses near infrared radiation. More specifically, two hard eye patches were attached to an eye mask according to the pupillary distance of the subject. The eye mask was held in place by an elastic headband. Each patch employed 19 light emitting diodes, emitting near infrared radiation from 850 nm to 1050 nm, with a peak at 940 nm. The device produced 10 mW/cm2 of energy operating on electrical power. Goto, E., et al., Treatment of Non-Inflamed Obstructive Meibomian Gland dysfunction by an Infrared Warm Compression Device, British Journal of Opthalmology, Vol. 86 (2002), pp. 1403-1407.
United States Patent Publication US2004/0237969 titled “Therapeutic Eye and Eye Lid Cover” comprises a pair of goggles that are adapted to deliver humid saturated air around the eyelids. This modality is also discussed in greater detail in the article titled “Tear Film Lipid Layer Thickness and Ocular Comfort after Meibomian Therapy via Latent Heat with a Novel Device in Normal Subjects by Mitra et al, published in Eye, (2004) at pages 1-4.
United States Patent Publication US2003/0233135 titled “Method and Apparatus for Preventing and Treating Eyelid Problems” by Yee attempts to clear the plugged meibomian glands by means of electrical stimulation of the muscle of Riolan which the invention presumed to aid in the expression of the meibomian gland secretion.
It will be noted that all of the above-noted treatment modalities are not without their inherent drawbacks and deficiencies. For example, the current application of heat to the meibomian glands treatment is very time consuming. Normally, treatment consists of at least fifteen minutes of heat application which is followed by manual expression, which normally consists of placing a cotton swab or firm surface behind the portion of the eye lid where the blocked meibomian gland is located and manually squeezing the obstruction from the gland, the foregoing often being quite painful despite the use of topical anesthesia provided in eye drop form.
It is therefore an object of the present invention to provide a meibomian gland treatment that overcomes the drawbacks and deficiencies of the prior art.
Another object of the present invention is to provide a meibomian gland treatment device that is a single step treatment, thus, eliminating the need for manual expression.
Yet another object of the present invention is to provide a meibomian gland treatment device which treats meibomian gland disease and not merely its symptoms.
Still another object of the present invention is to provide a meibomian gland treatment device that restores the natural sebum flow rather than merely attempting to replace or replicate the naturally occurring tear components.
A still further object of the present invention is to provide a meibomian gland treatment device which minimizes the chance of infection.
A still further object of the present invention is to provide a meibomian gland treatment device that is simple, inexpensive, and easy to use by the health care provider and the patient.